Voltage control of a locking differential

Abstract

A method for controlling a locking differential includes determining a temperature-dependent reference voltage at which a coil locks the differentia, determining an electric potential of a battery, using the battery to energize the coil and lock the differential, if the electric potential is equal to or greater than the reference voltage for a current temperature, and maintaining the differential unlocked, if the electric potential is less than the reference voltage.

1. A method for controlling a locking differential, comprising:
 (a) determining a temperature-dependent reference voltage at which a coil locks the differential; 
 (b) determining an electric potential of a battery; 
 (c) using the battery to energize the coil and lock the differential, if the electric potential is equal to or greater than the reference voltage for a current temperature; 
 (d) maintaining the differential unlocked, if the electric potential is less than the reference voltage. 
 
     
     
       2. The method of  claim 1  wherein step (a) further comprises defining reference voltages that correspond to temperatures of the coil over a range of such temperatures. 
     
     
       3. The method of  claim 1  wherein step (a) further comprises defining reference voltages that correspond to temperatures representative of the coil temperature. 
     
     
       4. The method of  claim 1  wherein step (a) further comprises defining a function that relates the reference voltage to a range of temperature representing the temperature of the coil. 
     
     
       5. The method of  claim 1  wherein step (b) further comprises using a battery charge indicator to determine an electric potential of the battery. 
     
     
       6. A system for controlling a locking differential, comprising:
 a coil for producing a magnetic field when energized by the battery; 
 a sensor indicating a temperature of the coil; 
 a battery; 
 a controller configured to determine a temperature-dependent reference voltage at which the coil lock the differential, determine an electric potential of the battery, to use the battery to energize the coil and lock the differential, if the electric potential is equal to or greater than the reference voltage for a current temperature, and to maintain the differential unlocked, if the electric potential is less than the reference voltage. 
 
     
     
       7. The system of  claim 6  wherein the controller is further configured to actuate and indicator that produces a sensible indication that the differential cannot be locked. 
     
     
       8. The system of  claim 6  wherein the controller is further configured to accessing a lookup table from which a temperature-dependent reference voltage at which the coil locks the differential is determined.